Wireless local area networks (WLANs), such as those based on the IEEE 802.11a, 802.11b and 802.11g standards, are becoming ubiquitous in business, government and small office/home office (SOHO) settings because of the freedom afforded by and the decreasing costs of the underlying technology. Current security mechanisms for maintaining the confidentiality, integrity, and availability of wireless communications within such networks are, however, flawed. For example, although the above-cited IEEE standards specify both an authentication service and encryption protocol for wireless networks, methods for compromising these security measures have been well publicized. In response, the community of wireless network equipment developers and vendors has started to adopt the authentication procedures outlined in the 2001 IEEE 802.1x standard entitled “Port Based Network Access Control” in an effort to provide solutions to these security defects. The facilities needed to deploy such access control measures, however, are both expensive and difficult for unsophisticated users to implement.
Before discussing the 802.1x access control mechanisms in detail, it is helpful to review some basics of WLANs in general. Unlike their wired LAN counterparts, WLANs provide for communication among network elements through wireless transmissions (e.g., radio transmissions), as opposed to wired, physical connections. FIG. 1 illustrates an exemplary prior art network 10 including a WLAN. In 802.11-based WLANs, clients or “stations” 12 (i.e., computers with wireless network interface cards (NICs)) interact with other network devices (printers, file servers, other clients, etc.) through access points (APs) 14, which act as bridges between the wired network 16 and wireless network 20. In some cases, wireless clients 12 may communicate directly with one another, without the use of APs.
The 802.1x standard does not itself specify any type of encryption procedures to be used within a network. To date, however, several equipment vendors have offered proprietary versions of dynamic key management for WLANs, using 802.1x as a delivery mechanism. In addition, the Wi-Fi Alliance (a non-profit industry consortium) has included 802.1x in its WPA security standard. Through dynamic key exchanges the authentication server 18 can return individual session keys to an AP 14 as part of the authentication process and these session keys can then be used for encrypted communications between the AP 14 and its clients 12. Dynamic key management provides a more secure environment than is typically found in an 802.11 WLAN because the use of multiple keys that are changed more frequently than is the case for a static key of an ordinary 802.11 network minimizes the opportunity for unauthorized users to uncover the keys.
Unfortunately, implementing an 802.1x solution for a WLAN is not an easy task. For example, the required network infrastructure is complex (potentially involving multiple authentication servers for use in cases of equipment failures) and expensive. In addition, installing the necessary hardware and software in the network and nodes thereof generally cannot be undertaken by unsophisticated users. Consequently, deployment of 802.1x compliant WLANs has not yet become widespread at an enterprise level and is virtually nonexistent at a SOHO level.